Secondary clock.



A L. SOHM.

SECONDARY CLOCK.

APPLICATION FILED MAYZI. m1.

1,302,605. Patnted May 6, 1919.

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UNITED STATES PATENT OFFICE.

ALFRED L. SOI-IM, OF CHICAGO, ILLINOIS, ASSIGNOB 'IO SOHM ELECTRIC COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

sncomm'ar CLOCK.

Specification of Letters Patent.

Patented May 6, 1919.

To all whom it may concern Be it known that I, ALFRED L. SoHM, a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented a certain new and useful Improvement in Secondary Clocks, of which the following is a full, clear, concise, and exact description, reference bein had to the accompanying drawings, forming a part of this specification.

My invention relates to secondary electromagnetic clocks.

The object of my invention is to provide an improved secondary clock mechanism and to produce a device which embodies the characteristics of simplicity, cheapness of manufacture and accuracy of operation. The manner in which these qualities are united in a secondary clock of what I believe to be hitherto unequaled fficiency will be understood from the followin specification taken in connection with t e accompanying drawings in which Figure 1 is a side elevational view of the complete operating mechanism attached to the dial of a clock with a part shown in section, and

Fig. 2 is a rear elevational view of the same with parts broken away and a part shown in section.

The frame of the clock comprises a rightangled bracket or supporting plate 1, the

vertical leg 2 of which is secured to the clock dial 3 in a plane parallel therewith by means of the posts 2, 2, and the screws 3. The horizontal leg 4 of the bracket serves as a support for a pair of electromagnets 5, 5.

The magnets are mounted upon the plate 4, their core'terminals 6, 6, projecting through apertures in the plate 4. An elongatedscrew 7 depending from the fixed bridge plate 8 of the magnet to the supporting plate 4 holds the magnets securely in place. This ma deslred manner. Suitable binding posts 9 are provided for connecting the magnets 1n the clock circuit.

Ears v10, 10, formed on the supportmg plate .4 are bent' over to form bearings for the armature 12, the pins 11, 11, of which serving as pivotal connection between the plate and armature. Felt pads 10, 10, or other suitable sound deadening devices may be inserted between the plate and armature. The end of the armature 12 farther from gnet mounting may be constructed in anythe fulcrum point 11 is fashioned into a rounded pin 13 which is adapted to be fitted into the eye in the rounded lower end 14 of an elongated operating member 15. This operating member 15 extends upwardlyfrom the armature through a slot in the supporting plate 4 and at its upper end is bifurcated, as seen in Fig. 2 to form the two fingers 16, 16, which are adapted to slide between the two flanges 17 of the U-shaped member 18. Member 17 serves not only as a guide for the fingers 16 and the operating member 15 but also as a means for spacing from the plate 2 a toothed wheel 20 which is mounted upon the minute hand shaft 21 of the clock mechanism. The wheel 20, on the side toward the magnet 5, is provided with a rounded hub 21 which has an axle 22, mounted in a bearing 23 provided by the lower end of a bracket 24 which extends upwardly from the bearing over the wheel 20 and is secured at its upper end to the supporting plate 2 by means of the pins 25, 25, and the screws 26, 26. The minute hand shaft 21 has a second bearing in the supporting plate 2 and extends through the same to a point outside the dial 3 where at its extremity the minute hand 30 is mounted and secured thereto by means of the thumb nut 31. Upon the shaft 21 and within the space between the plate 2 and the dial 3 is reduction gearing 31 which, as is well known, serves to transmit power to the gear 33 and the sleeve 34 to properly rotate the hour hand 35 mounted upon the extremity of the sleeve 34.

A tubular barrel 37 extends from a point near the lower end of the operating member 15 to which is pivotally mounted by means of'the screw 38 an upwardly extending advancing pawl 39, the pivot point 38 being in axial alinement with. the shaft 21, but not necessarily so. The helical spring 40 is placed within the barrel 37 and one end attached to the pawl 39, the other to the relatively fixed member 15. The action of this spring tends to rotate the pawl 39 in a counterclockwise direction. Motion in this direction is limited by the pin 42 which extends from the member 15, as seen in Fig. 2. A boss 43 is mounted on the member 15 at a point adjacent the operating end of pawl 39, from which protrudes an engaging member 44 beveled at its upper edge for engagement with the teeth 45 of the wheel 20. Ex-

' direction.

tending from pawl 39 and substantially at right angles therewith is an arm 46 which in the position of the operating member 15, as shown in Fig. 2, is located immediately below a similar arm 47 extending from a large holding pawl 48 which is mounted upon the vertical plate 2 by means of the tubular barrel 49 and pivoted thereto by means of the screw 50. 'As seen in Fig. 1, a spring 51 is disposed within the barrel 49 which spring is so connected with the stationary member and the pawl 48 that the latter tends to revolve in a clockwise direction so that its tooth 52 will always be engaged. between the teeth 45 of the wheel 20. While the pawl 48 is thus in engagement with the teeth of wheel 20, the shaft 21 will be locked and cannot be moved in either Should it be desired to revolve the shaft 21 for any reason, such as a resetting of the clock hands, the shaft 21 may be released by means of the mechanism shown in Fig. 2 which comprises a lever 54 extending from the pawl 48 at a point adjacent its pivotpoint 50 through the end of which lever a cord or wire 55 is fixed. It will be evident that a pull exerted on the cord '55 will rotate the pawl in a counterand the engaging member 43. As the member 15 and pawl 39 move upward, the arm 46 of the pawl 39 will-first engage the arm 47 of the pawl48 and rotate the same in a counterclockwise direction so that the teeth 45 of the wheel 20 are released during a slight amount of angular displacement of the pawls. 'Pawl 39 is so mounted on the memberle that at the precise moment when the tooth 52 of the holding pawl 48 is out of engagement with the teeth 45 of the wheel 20, the operating end of the advancing pawl; 39 engages the wheel 20 at a point between two of its teeth and rotates the wheel 20 in a counterclockwise direction as seen fron'ithe rear, as in Fig. 2. When the pawl 39 has rotated the wheel 20 a distance corresponding to a one minute movement of the clock hands, the stop 43 will have been sufficiently elevated to come in contact with the teeth 45 and prevent further movement thereof. It is to be noted that the arms 46 and 47 of the two pawls are in contact but an extremely short period of rotation of the same, in fact,

just suflicient amount for releasing the wheel 20 immediately after the pawl 39 has engaged'the teeth of the wheel 20. As soon as the pawl 39 has moved the teeth the arms 46yand- 47 pass each other and the pawl 48 is free to drop into the next space between thev teeth of the wheel 20. The engaging end of the pawl 39 is made larger than the space 'betweentwo teeth of the wheel 20,

as it is not necessary for the two members to be in mesh as the pawl 39 merely pushes the wheel around one space for each actuation.

It will now be evident that I have pro vided a double lock to guard against improper movement of the wheel 20. Ordinarily the pawl 48 is released by the pawl 39 immediately after the pawl 39 has engaged with the teeth 20 so that the pawl 48 is free to become engaged again in the next notch in the wheel 20. However, a double safe guard against overthrowing is provided by means of the stop member 43, for as the movement of the member 15 0011- tinues upward, the stop member 43 will be inserted between the teeth of the wheel 20 at-the precise time when the wheel has been the moving parts, which removes the stop member 43 as well as the pawl 39 from engagement with the teeth and the wheel 20 cannot be jarred or moved by this operation for the reason that the pawl 48 isin engage ment with the teeth preventing movement of the same in either direction. 7

It is to be noted that the illustrated embodiment of my invention is composed ofbut four operating parts, namely, the two pawls, the toothed wheel'and the operatingmember -15, all ofwhich maybe stamped out'of sheet metal. This simplicity enables me to manufacture the device with the leastipossi ble cost.

The double-locking means, above referred to, revents an inaccurate movement of the clock'hands for an impulse received by the magnets, for the wheel 20 must be advanced onei'nterval and not more than on'e interval for each movement of the magnet armature. 1

Due to the simplicity of arrangement and the limited number of parts, 'thedevi'ce is of very light construction and extremely compact. Two small screwsthrough the. clock dial to the vertical supporting plate will as shown in the drawings, for it will be apparent that changes may be made by those skilled in the art which I shall deem as coming within the scope of my invention.

What I claim is:

1. In a secondary clock mechanism, a toothed wheel for step-by-step rotation, an electromagnetically operated reciprocable member movable radially relatively to said wheel, a fixed plate, a spring pressed pawl pivoted to said plate and having an arm adapted to engage in the notches of said wheel to lock same against rotation, a spring pressed pawl carried by said member and having an arm adapted to engage the teeth of said wheel to rotate same, cooperating arms on said pawls for releasing the holding pawl in advance of the engagement of the operating pawl, and a rigid stop carried by said member adapted to engage the teeth of said wheel after the wheel has been rotated a predetermined amount to prevent overrotation thereof.

2. In a secondary clock mechanism, a

toothed wheel for step-by-step rotation, a gravity held wheel recpirocating member movable radially relatively to said wheel, a pair of ma nets for moving said actuating member, a xed plate, a spring pressed pawl pivotally mounted on said plate and having an arm for engagement with the teeth of said wheel for holding same against rotation, a spring pressed pawl carried by said reciprocable member having an arm for engagement with said wheel for rotating the wheel, said pawls having arms adapted for engagement as the reciprocable member is moved by said magnet to free the wheel from the holding pawl in advance of the engagement of the wheel by the moving pawl, and a stop carried by said reciprocable member for entering between the teeth of said wheel after same has been advanced one tooth to prevent overthrow of said wheel.

In witness whereof, I hereunto subscribe my name this 17th day of May, A. D. 1917.

ALFRED L. SOHM.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents. Washington, D. 0. 

